1902 Encyclopedia > Tides > [Dynamical Theory of Tides] Semi-Diurnal Tide, with Variable Depth

## Tides (Part 15)

III. DYNAMICAL THEORY OF TIDES (cont.)

15. Semi-Diurnal Tide, with Variable Depth

Next let us consider the semi-diurnal tide in the case where q = 1, so that γ = l sin2 θ. Then e = E sin2 θ, k = 2 , f = 1 ; also υ 0 = – e = – E sin2 θ. Hence by (28) and (26) – 8lυ0 + 4mlυ1 = 0, whence υ1 = 2/mυ0. Applying the same theorem a second time, υ2 = (2/m)2 υ0, If the height of tide is equal to the equilibrium height; but it is inverted, giving low water where the equilibrium theory gives high water. In the case of the earth m = 1/289, and therefore this relation is satisfied if l = a/1156. Hence in a sea 3000 fathoms deep at the equator, and shallowing to the poles, we have inverted semi-diurnal tides of the equilibrium height.

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